Soil & compost
Compost
Decomposed organic matter — kitchen and garden waste broken down into a dark, crumbly, sweet-smelling material that feeds soil and plants.
The word "compost" covers two different things, and it's worth knowing which is meant. Garden compost is the material you make yourself from waste. Bought compost — the bagged "multi-purpose" or seed compost you buy from a garden centre — is a growing medium for filling pots and trays. Always choose peat-free bags: peat extraction damages precious UK bogs, and every major retailer now stocks good peat-free ranges.
What you can compost
A healthy heap needs a rough balance of two types of material:
- Greens (soft, wet, nitrogen-rich): grass clippings, vegetable peelings, coffee grounds, spent plants, annual weeds.
- Browns (dry, woody, carbon-rich): cardboard, shredded paper, dead leaves, straw, woody prunings.
Aim for roughly equal amounts of each, or a touch more brown. Too many greens turns the heap into a slimy, smelly mess; too many browns and nothing rots. Avoid cooked food, meat and fish (they attract rats) and the roots of perennial weeds.
How a heap works
Microbes and worms break the material down, generating gentle heat as they go. Keep the heap moist but not soggy, and turn it every few weeks to add air and speed things up. In the UK, an active summer heap can produce usable compost in three to six months; a cold heap left untouched takes a year or more. You'll know it's finished when it's dark, crumbly and smells of woodland soil rather than rotting waste.
Using finished compost
Home-made compost is wonderfully versatile:
- As a soil improver, dug or forked into beds before planting.
- As a mulch, spread 5cm thick on the surface and left for the worms to pull down — the heart of no-dig gardening.
- As potting material, though home compost is usually too rich and variable for seeds, so mix it with bought peat-free compost rather than using it neat.
Not the same as manure or leaf mould
Manure is animal dung (often with bedding), which should be well-rotted for a year before use or it can scorch plants. Leaf mould is autumn leaves rotted down on their own — lower in nutrients but brilliant for soil structure and seed sowing. Both are great additions to a garden, but neither is the same as a balanced compost heap.
In a UK garden
In the UK's cool, damp climate a heap works fastest from late spring to early autumn and slows right down over winter, so most home compost is ready the following spring.
Example
Pile grass clippings and veg peelings in a corner bin through summer, turn it once or twice, and dig out dark crumbly compost the next March.